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(No Model.)

R. D. BALDWIN, F. DYLE 8U A'. A. THOMAS.

PURNAGE. No. 874,285. Patented Deo. 6, 1887.

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N. PETERS, Pnmvmhognphu, wnshingmm n.1;

UNITED STATES PATENT OFFICE.

RICHARD D. BALDWIN, FRANK DOYLE, lAND ADELBERT A. THOMAS, OF CHICAGO,ILLINOIS, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, TO JOHN W. TRAER,OF CEDAR RAPIDS, IOWA, AND SAID RICHARD BALDWIN.

FURNACE.

SPECIFICATION forming p'art of Letters Patent No. 374,285, datedDecember 6, 1887.

Application filed September 6, 1886. Serial No. 212,863.

To aZZ'whom it, may concern:

Beit known that we, RICHARD D. BALDWIN, FRANK DoYLE, and ADELEERT A.THOMAS, citizens of the United States, residing at Chicago, in thecounty of Cook and State of Illinois, have invented certain new anduseful Improvements in Furnaces, of which the followingis such a full,clear, and exact description of the invention as will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, which form a part ofthis specification, and in which similar letters of reference indicatelike parts throughout the several gures.

The object of the present invention is an improvement on the ordinarysteam-boiler or other furnace that will secure by its use a largeeconomy in the amount of fuel used and make available as fuel the lowergrade of coal, coaldust, and screenings not now generally used, and atthe same time combine all the advantages of a spark-arrester and asmokeconsumer, and which will cause the fuel t0 be so perfectly burnedas to reduce the quantity of ashes and cinder to a minimum. Theseobjects, as well as other advantages, we obtain by the novel devices andcombination of devices herein shown, described, and claimed.

In said drawings we have shown, in Figure 1, an ordinary steam-boilerfurnace to which our invention has been applied; in Fig. 2, a somewhatenlarged view of a portion of the same, both `being verticallongitudinal sectional views; and in Fig. 3, an enlarged trans`- versevertical sectional view of one ofthe gratebars on line 3 3 of Fig. 2.

The letter A represents the boiler; A, the usual masonry surrounding thesame; A2, the boiler-front, provided with fire and ash-pit doors A3 A,which open, respectively, into fire-chamber B and ash-pit B.

Upon the bridge-wall and extending across the width of the fire-surfaceis the receptacle C, in which one end of each of the grate-bars D issecured and supported. A second and somewhat smaller receptacle, C',secured to a projection, a, of the boiler-front below the fire- (Nomodel.)

slide-opening, c', by which the interior thereof 5 5 may be reachedandcleaned, as desired. A similar door or opening, c2, is provided for thesame purpose in the larger receptacle, C.

The grate-bars D are cast hollow throughout their entire length, and areprovided with strengthening-ribs d, as shown. The gratebars D are alsoprovided with an extension at each end cl d2, the one to fit into anopening in the receptacle C and the other into the opening c in thereceptacle C. It will be noticed that this opening or slot c is somewhatlarger than the extension, di, thus allowing for any expansion orcontraction which may take place in the grate-bars.

At suitable intervals in the upper surface of the grate-bars we providea series of holes or openings, d3, and we also prefer to make a portionof the lire-surface of said bars slightly concave, as shown.

The masonry A at the rear of the boiler A is so'constructed that all thesmoke, sparks, and flames of the burning fuel, after leaving thehre-chamber and passing to thc rear beneath the boiler, are not allowedto escape, but are directed into and through the tubes or fines in theboiler, and thence, passing upward and to the rear over the boiler, asindicated by arrows in Fig. l, enter the conduit E.

This conduit or pipe E is connected to an ordinary rotary fan, F,Vwhichin turn connects with one end of another conduit or pipe, E. llhis pipeE we usually place beneath the boiler, as shown, and connect its forwardend to the receptacle C. The fan F is operated by any convenientmeans-as, for example, by a belt and pulley, as illustrated. The receptacle C has a smaller pipe, e, connected to it, as shown, for the purposehereinafter to be eX- plained,which pipeis provided with adamper, c. Thereceptacle C may be provided with a lining of fire-clay, c3, as shown.

The operation of this invention is as follows: The fire being built onthe grate-loars in the iirechamber, the smoke, sparks, heated air, Src.,pass over the bridge-wall to the rear 5 of the boiler, thence throughthe tlues of the same out, and over the boiler to the pipeE, thencethrough the fan F into the pipe E', from whence they are forced into thereceptacle C. As soon as this receptacle G becomes lo iilled,the actionof the fan F causes the smoke,

sparks, Src., to seek outlet through the gratebars, and the continuedpressure forces the smoke, Snc., into the lire through the number ofsmall openings d3, already mentioned. The

Y ash-pit door A'1 may remain entirely open always,so asto admit freshair tothe fire throughthe interstices between the grate-bars, thelatterbeing usually about one-half inch apart.

The volume of fresh air is automatically reguzo lated by the fan F, thelire drawing in more air y or less, according as the blast is heavyorlight.

` The portions of fuel which are not completely burned at first are thusreturned to the tire in a number of small jets and impinge against theburning fuel remaining on the grates, be-

come ignited and consumed, or are again caused to make the circuitthrough the boiler,

fan, and receptacle C to the fire-chamber until entirely consumed orreduced to incombustible 3o matter, such as a very fine ash or toclinker.

With those fuels which evolve gases Vwhen burned in our furnace theresults have proved very satisfactory, as such gases readily mingle withthe smoke and make the circuit, passing out of the holes d3 of thegrate-bars, like so many gas-burners.

We have found by practical tests that furnaces equipped with ourinvention will completely burn or consume all the smoke and 4okcombustible matter in the fuel used in the fur naces, and completelyarrest all sparks or cinders from escape, thus effecting a large savingin fuel used over other furnaces having a chimney or smoke-stack,whereloy a large .1,5 amount of combustible matter, as well as heat,

escapes. Such incombustible gases as may sometimes be found in coal andother fuel are carried off by means ofthe .small pipe e to a chimney ordirectly to the outer air.

Ve do not intend to limit ourselves to the precise mechanism hereinillustrated, as many changes can be readily suggested by those skilledin the art, which changes and moditications may be usedvwithout at alldeparting 5 5 from the spirit and principle of our invention.

For example, we have shown the receptacle G as if made of cast metal;but it is obvious that the bridge-wall may be constructed intoareceptacle, having proper openings for the `be either a met-al pipe orbe built directly into pipes E and e and gratebars D, instead of 6osimply supporting the receptacle C, as illustrated in Fig. 1. The fan Fand pipe E may be placed inside instead of outside the masonry A', asshown, if preferred. The pipe E may 6 the wall of masonry. In somecasesit may not 5 be convenient to pass the smoke and dames back overthe top of the boiler, and in such cases we connect the conduit or pipeE to the front of the furnace immediatelyin rear of the boiler-front A2.Vhere the fire-chamber is very large, requiring a wide grate-surface, wefind it advantageous to divide or branch the pipe E', so as to supplythe receptacle Gat two or more points, and thus more evenly divide thesmoke and gases.

NVehave shown a stationary grate-bar; but it is obvious that a rockinggrate-bar can be used with equal advantage.

XVe also do not wish to be limited to the use of our invention asapplied to stationary-boiler furnaces, for it is equally applicable tolocomotive and other portable boilers. The receptacle C' receives suchparticles of cinders or sparks as do not find their way to theiirechamber through the holes d3.

In some cases where our invention is applied to furnaces already in usewe may not conveniently construct the masonry at the rear end oftheboiler, as shown at A', and in such cases the ordinary damper is used,so as to permit the closing of the connection between the smoke-finesand the chimney or stack when the blast or fan power is applied.

Having now described our invention, what we claim, and desire to secureby Letters Patent, is as follows:

1. In a furnace wherein the products Ofcom bustion are returned to thefire-chamber, the hollow grate-bar D, having extensions cl d at eitherend, and provided with a slightly-concave iresurface having aseries ofsmall holes or openings therein, in combination with receptacles C andG', substantially as shown and described.

2. In a furnace wherein the products of combustion are returned to thefire-chamber, the combination of the receptacle @,provided with pipe eand door c2, and of receptacle G, provided with door e', with the hollowperforated grate-bars having extensions dd2 at either end, substantiallyas shown and described.

RlGHARD D. BALDVIN. FRANK DOYLE. ADELBERT A. THOMAS. Vitnesses: JOHN M.GILL, TAYLOR E. BROWN.

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